The present invention relates generally to devices for measuring the rate of transmission of a gas or vapor through permeable packaging materials. More particularly, the invention relates to an apparatus for measuring water vapor concentrations in a gaseous medium under various flow conditions.
U.S. Pat. No. 3,902,068, issued Aug. 26, 1975, discloses a Method and Apparatus for Measuring Gas Transmission Through Packaging Materials, wherein an infrared analyzer is used in conjunction with a pumping system, wherein the pumping system cyclically increases and decreases the gas density within an absorption cell of the infrared gas analyzer. The present invention relates to the aforesaid patent, wherein it is contemplated to use a similar type infrared gas analyzer with pressure pulsations within the absorption cell. However, the aforesaid patent was concerned with measuring the permeation of various gases and vapors through packaging material by accumulation of gases, whereas the present invention relates to measuring water vapor transmission through packaging materials under dynamic flow conditions of a carrier gas.